When a freshly cut Christmas tree is placed in a stand, it initially consumes substantial quantities of water. The amount of water consumed however gradually diminishes with time. A typical Christmas tree stand is capable of holding only a limited amount of water, and therefore the water must be replenished fairly frequently, at least initially. The interior of a home in winter in a cold weather climate is also apt to have low humidity, and this can accelerate the loss of water. If a stand goes dry, the cut in the tree trunk also begins to dry to the detriment of the tree's vitality. Since the holiday season is often a busy time of year in many households, checking of the water level in a Christmas tree stand may be inadvertently neglected. In order to assist in maintaining the vitality of a cut tree for as long as possible, it has been proposed to provide a monitor for checking the water level in the stand. The monitor delivers a signal when the water drops to a level where it should be replenished.
The present invention is directed to a new and unique fluid level monitor that offers particular advantages for use with a Christmas stand, although uses of the invention can extend beyond this specific application.
For use with a Christmas tree stand, it is desirable that a fluid level monitor be battery operated. One reason for doing this is so that the monitor can continue to perform its monitoring function even when electric lights on the tree are turned off. In one respect the present invention provides a fluid level monitor that is battery operated. In the embodiment that is to be specifically disclosed herein, the monitor is powered by a conventional nine volt DC battery.
When a battery is used for powering the monitor, it is desirable that the battery voltage itself be monitored so that the opportunity will be available for an old battery to be replaced by a fresh one a certain amount of time before the monitoring function ceases due to low battery voltage. Another aspect of the invention relates to a battery-powered fluid level monitor in which the battery voltage is also monitored so that an opportunity is presented for replacing a weak battery that is in use before the battery ceases to be capable of operating the monitor.
A further aspect of the invention relates to the manner in which the monitor presents signals for conveying information about the status of the water level being monitored and of the monitor itself. This aspect includes both audible and visible signals that are uniquely related, and the electronic circuitry that is used to give these signals.
A still further aspect of the invention relates to the sensor that is disposed in the fluid whose level is being monitored. It is important that the sensor be sturdy enough to withstand the typical handling that is expected to encounter when placed in and removed from the fluid. It must also be capable of providing service in a fluid that is subject to the type of contamination that occurs when the cut trunk of a tree is placed in a stand of water. Should the sensor become contaminated, it should be able to be cleaned without unduly difficult procedures. And the de-fouling of the sensor should not expose the sensor to risk of damage.
When the invention is applied to a consumer product, as it would be when used for a Christmas tree stand, it must be cost-effective. The electronic circuitry that is used in the disclosed embodiment can be fabricated with the use of a fairly small number of commercially available components. Likewise the sensor is well suited for mass-production fabrication at a very reasonable cost, especially when compared to other commercially available sensors, or probes that are used for fluid level monitoring.
A still further feature of the invention relates to an implementation for a Christmas tree stand that divides the device into a first module that contains the electronics, and a second module that contains only the visible signal indicators and is plugged into the first module. The second module may be fabricated as a decorative ornament for attachment to the tree, while the first module is located elsewhere, such as being integrated into the stand itself, or in some way mounted on the stand. The first module could alternatively be located remote from the stand and tree.
The foregoing features, advantages, and benefits of the invention, along with additional ones, will be seen in the ensuing description and claims which should be considered in conjunction with the accompanying drawings. The drawings disclose a presently preferred embodiment of the invention according to the best mode contemplated at this time for carrying out the invention.